Gasoline composition containing tetravinyl lead and aromatic hydrocarbons



United States Patent GASOLINE CQMPOSITIQN CONTAINING TETRA- VINYL LEAD AND AROMATIC HYDRGCARBONS George J. Kantsky, El (Ierrito, Maurice R. Barusch, Richmond, and Wallace L. Richardson, Lafayette, Calif,

assignors to California Research Corporation, San

Francisco, Calif a corporation of Delaware No Drawing. Filed Mar. 31, 1960, Ser. No. 18,853

1 Qlaim. (Cl. 44-69) This invention relates to an improved gasoline composition. More particularly, the invention is concerned with a superior new hydrocarbon fuel of the gasoline boiling range containing tetravinyl lead.

Gasoline compositions of high octane number are commonly required for modern spark ignition internal combustion automobile and aircraft engines. Engines of these types in general use today are designed with high compression ratios for more eificient operation.

Since the present trend is toward engines of still higher compression ratios for increased power and improved performance, there is a constant demand for gasoline tives are greatly needed, therefore, to avoid present limitations and provide gasoline compositions of high octane number for future use in automobile and aircraft engines.

It has now been found that a superior new gasoline composition of high octane number is provided by a hydrocarbon base fuel boiling in the gasoline boiling range to which is added tetravinyl lead in amounts suflicient to improve the octane number, preferably, at least 0.5 milliliter per gallon of base fuel.

The improved gasoline compositions of the invention show unexpectedly high octane numbers compared to previously known combinations of hydrocarbon base fuels and additives. Hydrocarbon base fuels, together with the tetravinyl lead and mixtures thereof in accordance with the invention, have octane numbers which are substantially higher than similar base fuels employing the conventional lead tetraethyl additive in the same lead content. This is surprising since it has been generally accepted heretofore that other lead compounds are distinctly less efiicient than lead tetraethyl with respect to octane number improvement.

The hydrocarbon base fuel of the composition, according to the invention, is prepared by conventional refining and blending processes. It normally contains straight-chain paraflins, branched-chain paraifins, olefins, aromatics and naphthenes. Since straight-chain paraffins have a tendency to adversely affect octane number, the content of such hydrocarbons is ordinarily low.

As already mentioned, the base fuel is a hydrocarbon fuel boiling in the gasoline boiling range. Generally described, such fuels have an ASTM (D-86) distillation with an initial boiling point of about 100 F. and

a final boiling point of about 425 F. The unleaded base fuel preferably has a Research octane number of at least as determined by the accepted CFR engine test method. Also, the base fuel preferably contains at least 20% by volume of aromatic hydrocarbons. Less than 30% by volume of olefinic hydrocarbons are present in the fuel. The total paraflin and naphthene hydrocarbon content of the fuel may be as much as 80% by volume. For best overall engine performance, fuels containing in the range of 20 to 60% by volume of paraffinic and naphthenic hydrocarbons are preferred for volatility and other desirable gasoline characteristics. The more preferred hydrocarbon base fuels are those which contain from 20 to 60% by volume aromatic hydrocarbons and from 0 to 30% by volume of olefinic hydrocarbons. Most preferably, a gasoline having all-around desirable characteristics has a clear octane number of at least and contains about 50 to 60% by volume of parafiin and naphthene hydrocarbons, about 30 to 40% aromatic hydrocarbons and about 5 to 15% olefinic hydrocarbons.

For practical purposes, not more than about 4 milliliters of lead compounds per gallon is ordinarily used in the compositions. If desired, other octane-improving additives may be employed in addition to tetravinyl lead. These include other lead compounds such as lead tetraethyl, carbonyl derivatives of iron and cyclopentadienyl derivatives of metals such as manganese or iron. Other gasoline additives, such as scavengers like ethylene chloride or bromide, oxidation inhibitors, corrosion inhibitors, surface ignition suppressants like phosphorus compounds, detergents, and the like may be present.

The following example illustrates the preparation of tetravinyl lead compound in accordance with the inven tion. Unless otherwise specified, the proportions are on a weight basis.

EXAMPLE One liter of tetrahydrofuran is dried by distilling it from a mixture with lithium aluminum hydride. A 2- liter, 3-necked flask equipped with stirrer, addition funnel and reflux condenser, and purged continually with a slow stream of nitrogen, is charged with 30.2 grams 1.25 moles) of magnesium turnings and one small crystal of iodine. A solution of 134 grams (1.25 moles) of vinyl bromide in 200 ml. of the dried tetrahydrofuran is added, a few drops at a time, until the reaction starts. After the reaction is proceeding smoothly as evidenced by heat evolution, the mixture is cooled in ice and the addition continued at such a rate as to maintain the temperature at about 15 to 20 C. The addition requires about 1 /2 hours. The mixture is stirred an additional 6 hours at room temperature, following which the mixture is again cooled to 0 C. and diluted with an additional 300 ml. of tetrahydrofuran. Dried, powdered lead chloride (173 grams, 0.63 mole) is added over a tenminute period with vigorous stirring. Stirring is continued an additional hour at room temperature. Following the addition of 300 ml. of toluene, most of the watermiscible tetrahydrofuran is removed by distillation under reduced pressure. The mixture is again cooled in ice and 200 ml. of ice-cold distilled water is added over one-half hour. The mixture is poured into a beaker and 250 ml. of 2 N hydrochloric acid and 350 ml. of ethyl ether are added. The precipitated lead powder thus formed is removed by filtration. The organic phase is separated,

lead less the octane number obtained with the equivalent amount of lead tetraethyl.

washed with water and dried over anhydrous sodium sulfate. After removing ether and toluene solvents by distillation at reduced pressure, the product is fractionally distilled. The principal fraction boiling at 57 to 62 C. at 7 mm. Hg pressure weighs 44 grams. This is 45% of the theoretical yield based on starting reactants.

In further illustration of the superior new gasoline composition of the invention, several compositions and tests thereon are given in the following examples. These tests show the improved effect of the combination of the hydrocarbon base fuel with tetravinyl lead as compared with fuels containing other lead compounds.

The following table is a summary of the pertinent data of the examples. The type of compositions of the hydrocarbon base fuel is shown with respect to the percent by volume of the paratlins and naphthenes, olefins and aromatics. The clear octane number of the base fuel is also given. This octane number, as already mentioned, is the accepted Research octane number which is usually employed in designating a given gasoline. This method is described as Research Method D908 in ASTM Manual of Engine Test Methods for Rating Fuels.

The table shows the effect on octane number by the addition of certain amounts of lead tetravinyl as compared to lead tetraethyl. The octane number in this comparison is based on the Motor Method D357 of the ASTM Manual of Engine Test Methods for Rating Fuels. This method, which is more stringent than the Research Method, illustrates more accurately the desirable qualities of the improved gasoline composition of the invention.

In the table, the elfect of tetravinyl lead compared with lead tetraethyl is based on gasoline compositions containing an equal lead concentration. That is to say that about 3 milliliters per gallon of tetravinyl lead or 3.17 g. of lead as tetravinyl lead is compared with 3.00 milliliters per gallon lead tetraethyl. The Improvement" is the difference in the octane number obtained with tetravinyl The examples summarized in the above table show that the improved gasoline composition of the invention containing tetravinyl lead is decidedly better on the basis of octane number rating than comparable gasoline compositions of the type know heretofore. Surprisingly, another unsaturated alkyl lead compound, allyl trimethyl lead, in the fuel of Example 1 of the table, gave a Worse octane number than tetraethyl lead.

We claim:

A hydrocarbon fuel of the gasoline boiling range adapted for use as a fuel for spark ignition internal combustion engines having an octane number of at least 85 and containing at least 20% by volume of aromatic hydrocarbons, not more than 30% by volume of olefinic hydrocarbons and not more than 69% by volume of parafiinic and naphthenic hydrocarbons, said hydrocan' bon fuel having incorporated therein at least 0.5 milliliter and not more than about 4 milliliters of tetravinyl lead per gallon of hydrocarbon fuel.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Paper presented before 22nd Annual Meeting of the American Petroleum Institute, Nov. 7, 1941, Improved Motor Fuels Through Selective Blending, by Wagner et al., 19 pages.

Industrial and Engineering Chemistry, December 1948, 7

vol. 40, No. 12, Knocking Characteristics of Hydrocarbone, by Lovell, pages 2388-2397 (complete article pages 2388-2438). 

